package shujia;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.mapreduce.TableReducer;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;

import java.io.IOException;

public class Demo6MRReadAndWriteHBase {
    /**
     * 读写HBase
     * 读取student表 统计班级人数 结果保存回HBase
     */
    public static class ReadHBaseMapper extends TableMapper<Text, IntWritable> {
        @Override
        protected void map(ImmutableBytesWritable key, Result value, Mapper<ImmutableBytesWritable, Result, Text, IntWritable>.Context context) throws IOException, InterruptedException {
            String clazz = Bytes.toString(value.getValue("info".getBytes(), "clazz".getBytes()));

            context.write(new Text(clazz), new IntWritable(1));

        }
    }

    public static class WriteHBaseReducer extends TableReducer<Text, IntWritable, NullWritable> {
        @Override
        protected void reduce(Text key, Iterable<IntWritable> values, Reducer<Text, IntWritable, NullWritable, Mutation>.Context context) throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable v : values) {
                sum += v.get();
            }
            Put put = new Put(key.getBytes());
            put.addColumn("cf1".getBytes(), "cnt".getBytes(), (sum + "").getBytes());

            context.write(NullWritable.get(), put);
        }
    }

    public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
        Configuration conf = HBaseConfiguration.create();
        conf.set("hbase.zookeeper.quorum", "master:2181,node1:2181,node2:2181");

        Job job = Job.getInstance(conf);
        job.setJobName("Demo6MRReadAndWriteHBase");
        job.setJarByClass(Demo6MRReadAndWriteHBase.class);

        // 配置Map
        TableMapReduceUtil.initTableMapperJob(
                TableName.valueOf("student"),
                new Scan(),
                ReadHBaseMapper.class,
                Text.class,
                IntWritable.class,
                job
        );

        // 配置Reduce
        TableMapReduceUtil.initTableReducerJob(
                "clazz_cnt",
                WriteHBaseReducer.class,
                job
        );

        job.waitForCompletion(true);

    }
    /**
     * 先在HBase中把表创建好 create 'clazz_cnt','cf1'
     * 提交任务
     * hadoop jar HBase-1.0-jar-with-dependencies.jar com.shujia.Demo6MRReadAndWriteHBase
     */


}
